This invention relates to automatic power transmission, and more specifically to a detection system for detecting the level of power required for an internal combustion engine to deliver in proportion to varying loads and electrically actuating a control valve to vary the fluid pressure to effect automatic power transmission.
The conventional automatic power transmission of torque converter type involves the use of an intake vacuum sensor which includes a diaphragm responsive to the vacuum of the intake manifold to vary its position. The diaphragm is operatively connected to a valve member which controls the pressure of fluid used in the automatic power transmission mechanism, so that the fluid pressure is caused to vary in proportion to the sensed vacuum in the intake manifold.
However, the recent introduction of exhaust gas recirculation for reduction of NOx components and cylinder disablement control for fuel economy has caused the intake vacuum to deviate from the value that corresponds to the true indication of the engine load. Therefore, the intake vacuum is not available as a faithful representation of the engine load. As a result, the conventional automatic power transmission does not operate satisfactorily for an engine equipped with exhaust gas recirculation or cylinder disablement.